Uniterruptible power supply and its starting method

ABSTRACT

The present invention provides an uniterruptible electric power supply capable of inhibiting an excessively high intensity of inrush electric current at the time of start even when the inrush electric current inhibiting resistor  3  is not used.

TECHNICAL FIELD

The present invention relates to an uniterruptible electric power supplyin which a battery is built. In the case of electric power failure, ACelectric power is generated from this battery and supplied to electricequipment by this uniterruptible electric power supply. The presentinvention also relates to a method of starting the uniterruptibleelectric power supply.

BACKGROUND ART

FIG. 4 is an arrangement view showing an outline of the conventionaluniterruptible electric power supply.

In the view, reference numeral 1 is an AC electric power supply,reference numeral 2 is a condenser connected in parallel with the ACelectric power supply 1, reference numeral 3 is an inrush electriccurrent inhibiting resistor for inhibiting an inrush electric current,reference numeral 4 is a switch connected in parallel with the inrushelectric current inhibiting resistor 3, reference numeral 5 is anAC-electric-power-supply/battery changeover switch for changing overbetween the AC electric power supply and the battery, and referencenumeral 6 is a reactor for forming a filter together with the condenser2.

One end of the AC electric power supply 1 and one end of the AC outputare connected with each other by a common line, and a connecting pointof the first condenser 14 and the second condenser 15, which areconnected with each other in series, is connected with the common line.The other end of the AC electric power supply 1 is connected with theinrush electric current inhibiting resistor 3 and the switch 4 which isconnected in parallel with the inrush electric current inhibitingresistor 3. The contact “a” of the AC-electric-power-supply/batterychangeover switch 5 is connected with the inrush electric currentinhibiting resistor 3 and the switch 4, which is connected in parallelwith the inrush electric current inhibiting resistor 3, when the ACelectric power supply is turned on. The contact “b” is connected withthe battery operation switch 27 described later when the battery isturned on. The contact “c” is connected with the reactor 6.

Reference numerals 7, 8, 9 and 10 are diodes composing a diode bridge,and reference numeral 11 is a first semiconductor switch connected withthis diode bridge in parallel. The diode bridge, which is composed ofthe diodes 7, 8, 9 and 10, and the first semiconductor switch 11, whichis connected with the diode bridge in parallel, compose a convertersection and connect between one end of the reactor 6 and the commonline.

Reference numeral 12 is a first diode for preventing a back current,reference numeral 13 is a second diode for preventing a back current,reference numeral 14 is a first condenser connected between theP-voltage line and the common line, and reference numeral 15 is a secondcondenser connected between the common line and the N-voltage line.

Reference numeral 16 is a first semiconductor switch in the invertersection, reference numeral 17 is a diode connected in reverse parallelwith the semiconductor switch 16, reference numeral 18 is a secondsemiconductor switch in the inverter section, and reference numeral 19is a diode connected in reverse parallel with the semiconductor switch18. The semiconductor switch 16, diode 17, semiconductor switch 18 anddiode 19 compose an inverter section for converting DC electric power,which is sent from the DC electric power supply including the firstcondenser 14 and the second condenser 15, into AC electric power.

Reference numeral 20 is a filter composed of the reactor and condenser,and reference numeral 21 is a load.

Reference numeral 22 is a first semiconductor switch of the balancesection, reference 23 is a diode connected in reverse parallel with thesemiconductor switch 22, reference numeral 24 is a second semiconductorswitch of the balance section, reference numeral 25 is a diode connectedin reverse parallel with the semiconductor switch 24, and referencenumeral 26 is a reactor of the balance section.

The first semiconductor switch 22 of the balance section, one end (thecollector side in the drawing) of which is connected with P-voltage lineand the other end (the emitter side in the drawing) of which isconnected with one end (the collector side in the drawing) of the secondsemiconductor switch 24 of the balance section and also connected withthe reactor 26 of the balance section, the second semiconductor switch24 of the balance section, one end. (the collector side in the drawing)of which is connected with the other end of the first semiconductorswitch 22 of the balance section and also connected with the reactor 26of the balance section and the other end (the emitter side in thedrawing) of which is connected with N-voltage line, the back currentpreventing diode 23, the cathode side of which is connected with one end(collector side in the drawing) of the first semiconductor switch 22 ofthe balance section and the anode side of which is connected with theother end (emitter side in the drawing) of the first semiconductorswitch 22 of the balance section, the back current preventing diode 25,the cathode side of which is connected with one end (the collector sidein the drawing) of the semiconductor switch 24 of the balance sectionand the anode side of which is connected with the other end (the emitterside in the drawing) of the second semiconductor switch 24 of thebalance section, and the rector 26 of the balance section connectedbetween the connecting point, which connects the first semiconductorswitch 22 of the balance section and the second semiconductor switch 24of the balance section, and the common line, compose a balance sectionwhich moves an electric charge between the first condenser 14, which isconnected between P-voltage line and the common line, and the secondcondenser 15 connected between the common line and N-voltage line.

Reference numeral 27 is a battery operation switch, and referencenumeral 28 is a battery which is an electric power supply for supplyingelectric power in the case of electric power failure. The negativeelectrode side of the battery 28 is connected with the common line, andthe positive electrode side of the battery 28 is connected with thebattery operation switch 27 and one end (collector side in the drawing)of the negative electrode side boosting section semiconductor switch 29described later. Reference numeral 29 is a negative electrode sideboosting section semiconductor switch, and reference numeral 30 is anegative electrode side boosting section diode, and reference numeral 31is a negative electrode side boosting section reactor.

The battery 28, the negative electrode side boosting sectionsemiconductor switch 29, one end (the collector side in the drawing) ofwhich is connected with the positive electrode side of the battery 28and the other end (the emitter side in the drawing) of which isconnected with the negative electrode side boosting section reactor 31and negative electrode side boosting section diode 30, the negativeelectrode side boosting section reactor 31 connected between the otherend (the emitter side in the drawing) of the negative electrode sideboosting section semiconductor switch 29 and the common line, and thenegative electrode side boosting section diode 30 connected between theother end (the emitter side in the drawing) of the negative electrodeside boosting section semiconductor switch 29 and N-voltage line,compose an N-side boosting section.

Reference numeral 32 is a voltage detector for detecting voltage of thefirst condenser 14 and for detecting voltage of the second condenser 15.Reference numeral 33 b is a control circuit for controlling the switch 4connected in parallel with the inrush electric current inhibitingresistor 3, the AC-electric-power-supply/battery changeover switch 5,the battery operation switch 27, the first semiconductor switch 11, thefirst semiconductor switch 16 of the inverter section, the secondsemiconductor switch 18 of the inverter section, the first semiconductorswitch 22 of the balance section, the second semiconductor switch 24 ofthe balance section, and the negative electrode side boosting sectionsemiconductor switch 29.

The conventional uniterruptible electric power supply operates asfollows. The first condenser 14 and the second condenser 15 areelectrically charged by the AC electric power supply 1 (in the case ofnormal operation) or the battery 28 (in the case of electric powerfailure). In the inverter section including the first semiconductorswitch 16 of the inverter section, the diode 17, the secondsemiconductor switch 18 of the inverter section and the diode 19, DCelectric power sent from the DC electric power supply, which is composedof the first condenser 14 and the second condenser 15, is converted intoAC electric power. The thus converted AC electric power is supplied tothe load 21.

FIGS. 5 and 6 are views for explaining operation of electrical chargingconducted by the AC electric power supply 1 in the conventionaluniterruptible electric power supply. In the views, reference numerals 1and 3 to 15 are the same as those shown in FIG. 4. Therefore,explanations are omitted here.

Referring to FIGS. 4, 5 and 6, an electrically charging motion of theconventional uniterruptible electric power supply in the case of normaloperation will be explained below.

In the case of normal operation conducted by the AC electric powersupply 1, in the start of operation in which theAC-electric-power-supply/battery changeover switch 5 is set on thecontact “a” side, the first condenser 14 and the second condenser 15have not been electrically charged yet. Therefore, in order to inhibitan inrush electric current flowing into the first condenser 14 and thesecond condenser 15, the switch 4 is opened which is connected inparallel with the inrush electric current inhibiting resistor 3.

In the case where the AC electric power supply 1 generates a positivevoltage, the first semiconductor switch 11 is turned on, and electricenergy is stored in the reactor 6 by the route of the AC electric powersupply 1→the inrush electric current inhibiting resistor 3 in the caseof starting→the AC-electric-power-supply/battery changeover switch 5→thereactor 6→the diode 7 of the diode bridge→the first semiconductor switch11→the diode 10 of the diode bridge→the AC electric power supply 1 asshown in FIG. 5A. Successively, the first semiconductor switch 11 isturned off and electric energy stored in the reactor 6 is charged intothe first condenser 14 by the route of the reactor 6→the first diode 12for preventing a back current→the first condenser 14→the AC electricpower supply 1→the inrush electric current inhibiting resistor 3→theAC-electric-power-supply/battery changeover switch 5→the reactor 6, andthe P-voltage line is formed with respect to the common line as shown inFIG. 5B.

In the case where the AC electric power supply 1 generates a negativevoltage, the first semiconductor switch 11 is turned on, and electricenergy is stored in the reactor 6 by the route of the AC electric powersupply, →the diode 8 of the diode bridge→the first semiconductor switch11→the diode 9 of the diode bridge→the reactor 6→theAC-electric-power-supply/battery changeover switch 5→the inrush electriccurrent inhibiting resistor 3→the AC electric power supply 1 as shown inFIG. 6A. Successively, the first semiconductor switch 11 is turned off,and electric energy stored in the reactor 6 is charged into the secondcondenser 15 by the route of the reactor 6→theAC-electric-power-supply/battery changeover switch 5→the inrush electriccurrent inhibiting resistor 3→the AC electric power supply 1→the secondcondenser 15→the second diode 13 for preventing a back current→thereactor 6, and the N-voltage line is formed with respect to the commonline as shown in FIG. 6B.

When voltage of the first condenser 14 and voltage of the secondcondenser 15 are higher than the peak value of the AC electric powersupply 1, for example, when voltage of the first condenser 14 andvoltage of the second condenser 15 are 141 V in the case of operation of100 V or when voltage of the first condenser 14 and voltage of thesecond condenser 15 are 180 V in the case of operation of 120 V, theswitch 4 is short-circuited.

In the case of normal operation conducted by the AC electric powersupply 1, after voltage of the first condenser 14 and voltage of thesecond condenser 15 have become higher than the peak value of the ACelectric power supply 1, an electrically charging motion is executed bythe route in which the above inrush electric current inhibiting resistor3 is replaced with the switch 4.

In the case where the AC electric power supply 1 generates a positivevoltage, the first semiconductor switch 11 is turned on, and electricenergy is stored in the reactor 6 by the route of the AC electric powersupply 1→the switch 4→the AC-electric-power-supply/battery changeoverswitch 5→the reactor 6→the diode 7 of the diode bridge→the firstsemiconductor switch 11→the diode 10 of the diode bridge→the AC electricpower supply 1 as shown in FIG. 5A. Successively, the firstsemiconductor switch 11 is turned off, and electric energy stored in thereactor 6 is charged into the first condenser 14 by the route of thereactor 6→the first diode 12 for preventing a back current→the firstcondenser 14→the AC electric power supply 1→the switch 4→theAC-electric-power-supply/battery changeover switch 5→the reactor 6, andthe P-voltage line is formed with respect to the common line as shown inFIG. 5B.

In the case where the AC electric power supply generates a negativevoltage, the first semiconductor switch 11 is turned on, and electricenergy is stored in the reactor 6 by the route of the AC electric powersupply 1→the diode 8 of the diode bridge→the first semiconductor switch11→the diode 9 of the diode bridge→the reactor 6→theAC-electric-power-supply/battery changeover switch 5→the switch 4→the ACelectric power supply 1 as shown in FIG. 6A. Successively, the firstsemiconductor switch 11 is turned off, and electric energy stored in thereactor 6 is charged into the second condenser 15 by the route of thereactor 6→the AC-electric-power-supply/battery changeover switch 5→theswitch 4→the AC electric power supply 1→the second condenser 15→thesecond diode 13 for preventing a back current→the reactor 6, and theN-voltage line is formed with respect to the common line as shown inFIG. 6B.

FIGS. 7 and 8 are views for explaining an electrically charging motionconducted by the battery 28 of the conventional uniterruptible electricpower supply. In the views, reference numerals 5 to 7, 10 to 12, 14, 15and 27 to 31 are the same as those shown in FIG. 4. Therefore, theexplanations are omitted here.

Referring to FIGS. 4, 7 and 8, explanations will be made into theelectrically charging motion conducted by the battery in theconventional uniterruptible electric power supply in the case ofelectric power failure.

In the case of electric power failure, theAC-electric-power-supply/battery changeover switch 5 is changed over tothe contact “b” side, so that the battery operation switch 27 isshort-circuited.

The first semiconductor switch 11 is turned on, and electric energy isstored in the reactor 6 by the route of the battery 28→the batteryoperation switch 27→the AC-electric-power-supply/battery changeoverswitch 5→the reactor 6→the diode 7 of the diode bridge→the firstsemiconductor switch 11→the diode 10 of the diode bridge→the battery 28as shown in FIG. 7A. Successively, the first semiconductor switch 11 isturned off, and electric energy stored in the reactor 6 is charged intothe first condenser 14 by the route of the reactor 6→the first diode 12for preventing a back current→the first condenser 14→the battery 28→thebattery operation switch 27→the AC-electric-power-supply/batterychangeover switch 5→the reactor 6 as shown in FIG. 7B.

The negative electrode side boosting section semiconductor switch 29 isturned on, and electric energy is stored in the negative electrode sideboosting section reactor 31 by the route of the battery 28→the negativeelectrode side boosting section semiconductor switch 29→the negativeelectrode side boosting section reactor 31→the battery 28 as shown inFIG. 8A. Successively, the negative electrode side boosting sectionsemiconductor switch 29 is turned off, and electric energy stored in thenegative electrode side boosting section reactor 31 is charged into thesecond condenser 15 by the route of the negative electrode side boostingsection reactor 31→the second condenser 15→the negative electrode sideboosting section diode 30→the negative electrode side boosting sectionreactor 31 as shown in FIG. 8B.

By using the voltage of the first condenser 14 and voltage of the secondcondenser 15 which are electrically charged in the above way, DCelectric power is converted into AC electric power by the invertersection, so that AC electric power is supplied to the load 21. However,in the case where voltage of the first condenser 14 and voltage of thesecond condenser 15 are not balanced to each other by the unbalance ofthe load 21, electrical charges of the first condenser 14 and the secondcondenser 15 are moved by the action of the balance section which iscomposed of: the first semiconductor switch 22 of the balance sectionand the second semiconductor switch 24 of the balance section connectedin series between P-voltage line and N-voltage line; and the balancesection reactor 26 connected between the contact point, at which thefirst semiconductor switch 22 of the balance section is contacted withthe second semiconductor switch 24 of the balance section, and thecommon line.

In the conventional uniterruptible electric power supply, at the time ofstart in which the first condenser 14 and the second condenser 15 arenot electrically charged, in the case of connecting with the AC electricpower supply 1, an inrush electric current flows in the first condenser14 and the second condenser 15. In order to inhibit the intensity of theinrush electric current flowing in the first condenser 14 and the secondcondenser 15, it is necessary to use the inrush electric currentinhibiting resistor 3 for inhibiting the inrush electric current flowingat the time of start. Since the inrush electric current inhibitingresistor 3 consumes a high intensity of electric power, the size of theresistor 3 is large. Further, the inrush electric current inhibitingresistor 3 consumes a high intensity of electric power and generates alarge quantity of heat. Therefore, it is difficult to reduce the size ofthe uniterruptible electric power supply.

The present invention has been accomplished to solve the aboveconventional problems. It is an object to provide an uniterruptibleelectric power supply capable of inhibiting an excessively highintensity of inrush electric current at the time of start even when theinrush electric current inhibiting resistor 3 is not used.

DISCLOSURE OF THE INVENTION

The present invention provides an uniterruptible electric power supplycomprising: a converter section for converting AC electric power of anAC electric power supply into DC electric power; a battery used as anelectric power supply in the case of start and also in the case ofelectric power failure; a condenser for storing DC voltage converted bythe converter section or DC voltage supplied from the battery; aninverter section for converting DC voltage of the condenser into ACelectric power; and a control section for controlling so that thecondenser is electrically charged by the battery and the electric powersupply is changed over from the battery to the AC electric power supplyafter voltage of the condenser has reached a predetermined value. Due tothe above constitution, even when an inrush electric current inhibitingresistor is not used, it is possible to prevent an inrush electriccurrent from flowing into the condenser which is not electricallycharged at the time of start.

The present invention provides a method of starting an uniterruptibleelectric power supply, at the time of start in which a condenser, whichbecomes a DC electric power supply of an inverter section for convertingDC voltage into AC electric power, is not electrically charged,comprising the steps of: charging the condenser by a battery; andchanging over from the battery to an AC electric power supply after thecondenser has been charged to a predetermined voltage. Due to the aboveconstitution, even when an inrush electric current inhibiting resistoris not used, it is possible to prevent an inrush electric current fromflowing into the condenser which is not electrically charged at the timeof start.

Further, the present invention provides an uniterruptible electric powersupply comprising: a common line for connecting one end of an ACelectric power supply with one end of an AC output; a positive electrodeside voltage line and a negative electrode side voltage line whichrespectively become a positive electrode side and a negative electrodeside of DC formed at both ends of diodes connected with each other inseries, a connecting point of the diodes connected with each other inseries being connected with the other end of the AC electric powersupply; a first condenser connected between the common line and thevoltage line on the positive electrode side; a second electrodeconnected between the common line and the voltage line on the negativeelectrode side; a battery, the negative electrode side of which isconnected with the common line; a negative electrode side boostingsection semiconductor switch, one end collector side of which isconnected with the positive electrode side of the battery; a negativeelectrode side boosting section reactor connected between the other endemitter side of the negative electrode side boosting sectionsemiconductor switch and the common line; a negative electrode sideboosting section diode, one end on the cathode of which is connectedwith the other end on the emitter side of the negative electrode sideboosting section semiconductor switch, the other end on the anode sideof which is connected with the negative electrode voltage line; a firstsemiconductor switch of a balance section and a second semiconductorswitch of the balance section connected with each other in seriesbetween the positive electrode voltage line and the negative electrodevoltage line; a first diode of the balance section and a second diode ofthe balance section which are respectively connected with the firstsemiconductor switch of the balance section and the second semiconductorswitch of the balance section in reverse parallel with each other; areactor of the balance section connected between a contacting point, atwhich the first semiconductor switch of the balance section and thesecond semiconductor switch of the balance section are contacted witheach other, and the common line; and a control section for turning onand off the negative electrode side boosting section semiconductorswitch and the second semiconductor switch of the balance section,wherein after the second condenser is electrically charged by thebattery when the negative electrode side boosting section semiconductorswitch is turned on and off at the time of start, the secondsemiconductor switch of the balance section is turned on and off so asto electrically charge the first condenser by utilizing voltage of thesecond condenser.

Due to the above constitution, it becomes unnecessary to giveconsideration to the heat generated from an inrush electric currentinhibiting resistor. Therefore, a size of the uniterruptible electricpower supply can be reduced.

Further, the present invention provides an uniterruptible electric powersupply, in which the control section changes over the electric powersupply to the AC electric power supply after voltage of the firstcondenser and voltage of the second condenser are equilibrated to eachother and raised to a predetermined voltage.

Due to the above constitution, it is possible to provide anuniterruptible electric power supply capable of smoothly changing overthe input of electric power from the battery to the AC electric powersupply.

The present invention provides a method of starting an uniterruptibleelectric power supply comprising: a first step in which a secondcondenser is electrically charged to a voltage not lower than apredetermined voltage by using a battery at the time of start in which afirst condenser connected between a common line, which connects one endof an AC electric power supply with one end of an AC output, and apositive electrode voltage line is not electrically charged and thesecond condenser connected between the common line and the negativeelectrode voltage line is not electrically charged; a second step inwhich the first condenser is electrically charged by utilizing voltageof the second condenser until voltage of the first condenser and voltageof the second condenser are equilibrated to each other; and a third stepin which processing of the first and second steps is successivelyconducted until voltage of the first condenser and voltage of the secondcondenser are raised to a value not lower than a predetermined value,and electric power input is changed over from the battery to the ACpower supply at the point of time when voltage of the first condenserand voltage of the second condenser are raised to a value not lower thana predetermined value. Therefore, after the uniterruptible electricpower supply is started by the input from the battery, it can besmoothly changed over to the input from the AC electric power supply.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an arrangement view showing an outline of the uniterruptibleelectric power supply of Embodiment 1 of the present invention.

FIG. 2 is a flow chart for explaining an electrically charging motionconducted by the battery 28 at the time of start in the uniterruptibleelectric power supply of Embodiment 1 of the present invention.

FIGS. 3A and 3B are views for explaining an electrically charging motionto charge the first condenser 14 in the uniterruptible electric powersupply of. Embodiment 1 of the present invention.

FIG. 4 is an arrangement view showing an outline of the conventionaluniterruptible electric power supply.

FIGS. 5A and 5B are views for explaining an electrically charging motionconducted by the AC electric power supply 1 in the conventionaluniterruptible electric power supply.

FIGS. 6A and 6B are views for explaining an electrically charging motionconducted by the AC electric power supply 1 in the conventionaluniterruptible electric power supply.

FIGS. 7A and 7B are views for explaining an electrically charging motionconducted by the battery 28 in the conventional uniterruptible electricpower supply.

FIGS. 8A and 8B are views for explaining an electrically charging motionconducted by the battery 28 in the conventional uniterruptible electricpower supply.

BEST MODE FOR CARRYING OUT THE INVENTION

Embodiment 1

FIG. 1 is an arrangement view showing an outline of the uniterruptibleelectric power supply of Embodiment 1 of the present invention. In theview, reference numerals 1, 2 and 5 to 32 represent the same componentsas those shown in FIG. 4. Therefore, the explanations are omitted here.Reference numeral 33 a is a control circuit for controlling anAC-electric-power-supply/battery changeover switch 5, a firstsemiconductor switch 11, a first semiconductor switch 16 of the invertersection, a second semiconductor switch 18 of the inverter section, afirst semiconductor switch 22 of the balance section, a secondsemiconductor switch 24 of the balance section, a battery operationswitch 27 and a negative electrode side boosting section semiconductorswitch 29.

In the uniterruptible electric power supply of Embodiment 1, the battery28 is used at the time of start so as to electrically charge the firstcondenser 14 and the second condenser 15, and then the AC electric powersupply is connected.

The uniterruptible electric power supply of Embodiment 1 shown in FIG. 1is composed as follows. The inrush electric current inhibiting resistor3 for inhibiting an intensity of the inrush electric current and theswitch 4 connected in parallel with the inrush electric currentinhibiting resistor 3 are deleted from the constitution of theconventional uniterruptible electric power supply shown in FIG. 4, andthe control circuit 33 b (for controlling the switch 4, theAC-electric-power-supply/battery changeover switch 5, the batteryoperation switch 27; the first semiconductor switch 11, the firstsemiconductor switch 16 of the inverter section, the secondsemiconductor switch 18 of the inverter section, the first semiconductorswitch 22 of the balance section, the second semiconductor switch 24 ofthe balance section, and the negative electrode side boosting sectionsemiconductor switch 29) is replaced with the control circuit 33 a (forcontrolling the AC-electric-power-supply/battery changeover switch 5,the battery operation switch 27, the first semiconductor switch 11, thefirst semiconductor switch 16 of the inverter section, the secondsemiconductor switch 18 of the inverter section, the first semiconductorswitch 22 of the balance section, the second semiconductor switch 24 ofthe balance section, and the negative electrode side boosting sectionsemiconductor switch 29).

However, in Embodiment 1, the contact “a” of theAC-electric-power-supply/battery changeover switch 5 is connected withthe condenser 2 connected in parallel with the AC electric power supply1 in the case of inputting electric power from the AC electric powersupply, the contact “b” is contacted with the battery operation switch27 in the case of inputting electric power from the battery, and thecontact “c” is connected with the reactor 6.

A motion of electrically charging the first condenser 14 and the secondcondenser 15 conducted by the AC electric power supply in the normaloperation, in which the AC-electric-power-supply/battery changeoverswitch 5 is set on the contact “a” side, is the same as the motionconducted while the inrush electric current inhibiting resistor 3 forinhibiting an inrush electric current and the switch 4, which isconnected in parallel with the inrush electric current inhibitingresistor 3, are deleted from the conventional constitution shown inFIGS. 5(a), 5(b), 6(a) and 6(b).

In the case where the AC electric power supply 1 generates a positivevoltage, the first semiconductor switch 11 is turned on, and electricenergy is stored in the reactor 6 by the route of the AC electric powersupply 1→the AC-electric-power-supply/battery changeover switch 5→thereactor 6→the diode 7 of the diode bridge→the first semiconductor switch11→the diode 10 of the diode bridge→the AC electric power supply 1.Successively, the first semiconductor switch 11 is turned off, andelectric energy stored in the reactor 6 is electrically charged into thefirst condenser 14 by the route of the reactor 6→the first diode 12 forpreventing a back electric current→the first condenser 14→the ACelectric power supply 1→the AC-electric-power-supply/battery changeoverswitch 5→the reactor 6, and the P-voltage line is formed with respect tothe common line.

In the case where the AC electric power supply generates a negativevoltage, the first semiconductor switch 11 is turned on, and electricenergy is stored in the reactor 6 by the route of the AC electric powersupply 1→the diode 8 of the diode bridge→the first semiconductor switch11→the diode 9 of the diode bridge→the reactor 6→theAC-electric-power-supply/battery changeover switch 5→the AC electricpower supply 1. Successively, the first semiconductor switch 11 isturned off, and electric energy stored in the reactor 6 is electricallycharged into the second condenser 15 by the route of the reactor 6→theAC-electric-power-supply/battery changeover switch 5→the AC electricpower supply 1→the second condenser 15→the second diode 13 forpreventing a back current→the reactor 6, and the N-voltage line isformed with respect to the common line.

A motion of electrically charging the first condenser 14 and the secondcondenser 15 conducted by the battery 28 in the case of electric powerfailure is the same as that of the conventional example shown in FIGS.7(a), 7(b), 8(a) and 8(b), and the explanations are omitted here.

FIG. 2 is a flow chart for explaining an electrically charging motionconducted by the battery 28 at the time of start in the uniterruptibleelectric power supply of Embodiment 1 of the present invention.

In the uniterruptible electric power supply of Embodiment 1, a motion ofelectrically charging the second condenser 15 by the battery 28 at thetime of start is the same as the motion of electrically charging thesecond condenser 15 by the battery 28 at the time of electric powerfailure in the conventional example shown in FIGS. 8A and 8B.

FIGS. 3A and 3B are views for explaining an electrically charging motionto charge the first condenser 14 in the uniterruptible electric powersupply of Embodiment 1 of the present invention. In the view, referencenumerals 14, 15, 23, 24 and 26 represent the same components as thoseshown in FIG. 1. Therefore, the explanations are omitted here.

At the time of start, the first condenser 14 is not electrically chargedat all. When a motion of electrically charging the first condenser 14 bythe battery 28 conducted in the case of electric power failure is usedat the time of start, an inrush electric current flows into the firstcondenser 14 by the route of the battery 28→the battery operation switch27→the AC-electric-power-supply/battery changeover switch 5→the reactor6→the first diode 12 for preventing a back electric current→the firstcondenser 14→the battery 28 as shown in FIG. 7B of the conventionalexample.

Accordingly, at the time of electric power failure, theAC-electric-power-supply/battery changeover switch 5 is changed over tothe contact “b” side so as to short-circuit the battery operation switch27. However, at the time of start of the uniterruptible electric powersupply of Embodiment 1, the battery operation switch 27 is kept open,and the second condenser 15 is electrically charged by the battery 28.After that, by using the balance section including the firstsemiconductor switch 22 of the balance section, the diode 23, the secondsemiconductor switch 24 of the balance section, the diode 25 and thereactor 26 of the balance section, an electric charge is moved from thesecond condenser 15 to the first condenser 14, so that the firstcondenser 14 is electrically charged.

The N-side boosting section for electrically charging and boosting thesecond condenser 15 connected between the common line and N-voltageline, includes: the battery 28, the negative side of which is connectedwith the common line, the positive side of which is connected with oneend (the collector side in the drawing) of the negative electrode sideboosting section semiconductor switch 29; the negative electrode sideboosting section semiconductor switch 29, one end (the collector side inthe drawing) of which is connected with the positive electrode side ofthe battery 28 and the other end (the emitter side in the drawing) ofwhich is connected with the negative electrode side boosting sectionreactor 31 and the cathode side of the negative electrode side boostingsection diode 30; the negative electrode side boosting section diode 30,the cathode side of which is connected with the other end (the emitterside in the drawing) of the negative electrode side boosting sectionsemiconductor switch 29 and the anode side of which is connected withthe N-voltage line; and the negative electrode side boosting sectionreactor 31 connected between the other end (the emitter side in thedrawing) of the negative electrode side boosting section semiconductorswitch 29 and the common line.

Referring to FIGS. 1 to 3 and 8, a motion of the uniterruptible electricpower supply of Embodiment 1 at the time of start will be explained asfollows.

At the time of start when the first condenser 14 and the secondcondenser 15 are not electrically charged at all, the control circuit 33a changes over the first switch 5 to the contact “b” side and opens thebattery operation switch 27 at the same time.

In step S1, as shown in FIGS. 8A and 8B, the control circuit 33 a turnson and off the negative electrode side boosting section semiconductorswitch 29 by using the battery 28, so that the second condenser 15 iselectrically charged. At the time of start, the condenser iselectrically charged by the battery 28 as follows.

While the negative electrode side boosting section semiconductor switch29 is kept being turned on, electric energy is stored in the negativeelectrode side boosting section reactor 31 by the route of the battery28→the negative electrode side boosting section semiconductor switch29→the negative electrode side boosting section reactor 31→the battery28 as shown in FIG. 8A. Next, the negative electrode side boostingsection semiconductor switch 29 is turned off, and electric energystored in the negative electrode side boosting section reactor 31 iselectrically charged into the second condenser 15 by the route of thenegative electrode side boosting section reactor 31→the second condenser15→the negative electrode side boosting section diode 30→the negativeelectrode side boosting section reactor 31 as shown in FIG. 8B.

Successively, in step S2, it is judged whether or not voltage of thesecond condenser 15 is raised to be not lower than a predeterminedvalue, for example, in the case of operation at 100 V, it is judgedwhether or not voltage of the second condenser 15 is raised to be notlower than 141 V, in the case of operation at 120 V, it is judgedwhether or not voltage of the second condenser 15 is raised to be notlower than 180 V. In the case where voltage of the second condenser 15is lower than the predetermined value, the program returns to step S1,and the second condenser is electrically charged by the battery 28. Thebattery 28, the negative electrode side boosting section semiconductorswitch 29, the negative electrode side boosting section reactor 31, thesecond condenser 15 and the negative electrode side boosting sectiondiode 30 compose an inversion chopper circuit. When the negativeelectrode side boosting section semiconductor switch 29 is controlledbeing turned and on and off, voltage of the second condenser 15 israised to an arbitrary voltage.

In the case where voltage of the second condenser 15 is not lower thanthe predetermined value in step S2, successively in step S3, the secondsemiconductor switch 24 of the balance section is controlled beingturned on and off as shown in FIGS. 3A and 3B, and the first condenser14 is electrically charged by the second condenser 15 so that voltage ofthe first condenser 14 can be the same as that of the second condenser15. A motion of charging the first condenser 14 by the second condenser15 is described below.

While the second semiconductor switch 24 of the balance section is keptbeing turned on, electric energy is stored in the reactor 26 of thebalance section by the route of the second condenser 15→the rector 26 ofthe balance section→the second semiconductor switch 24 of the balancesection→the second condenser 15 as shown in FIG. 3A. Successively, whilethe semiconductor switch 24 of the balance section is being kept turnedoff, electric energy stored in the reactor 26 of the balance section ischarged into the first condenser 14 by the route of the reactor 26 ofthe balance section→the diode 23 of the balance section→the firstcondenser 14→the reactor 26 of the balance section as shown in FIG. 3B.

When the second semiconductor switch 24 of the balance section iscontrolled being turned on and off, voltage of the first condenser 14 israised to an arbitrary value.

In step S4, the control circuit 33 a judges whether or not voltage ofthe first condenser 14 and voltage of the second condenser 15 areequilibrated to each other. In the case where voltage of the firstcondenser 14 and voltage of the second condenser 15 are not equilibratedto each other, the program returns to step S3, and the semiconductorswitch 24 of the balance section is controlled being turned on and offas shown in FIGS. 3A and 3B, so that the first condenser 14 iselectrically charged by the second condenser 15.

In step S5, the control circuit 33 a judges whether or not voltage ofthe first condenser 14 and voltage of the second condenser 15 are raisedto be not lower than a predetermined value, for example, in the case ofoperation at 100 V, the control circuit 33 a judges whether or notvoltage of the first condenser 14 and voltage of the second boostingsection reactor 31, the second condeser 15 and the negative electrodeside boosting section diode 30 compose an inversion chopper cicuit. Whenthe negative controlled being turned on and off, voltage of the secondcondenser 15 is raised to an arbitrary voltage.

In the case where voltage of the second condenser 25 is not lower thatthe predetermined value in step S2, successively in step S3, the secondsemiconductor switch 24 of the balance section is controlled beingturned on and off as shown in FIGS. 3A and 3B, and the first condenser14 is electrically changed by the second condenser 15 so that voltage ofthe first condenser 14 can be the same as that of the second condenser.A motion of charging the first condenser 14 by the second condenser 15is described below.

While thesecond semiconductor switch 24 of the balance section is keptbeing turned on, electric energy is stored in the reactor 26 of thebalance section by the route of the second condenser 15→the reactor 26of the balance section→the second condenser 15 as shown in FIG. 3A.Successsively, while the semiconductor switch 24 of the balance sectionis being kept turned off, electric energy is stored in the reactor 26 ofthe balance section is charged into the first condenser 14 by the routeof the reactor 26 of the balance section→the diode 23 of the balancesection→the first condenser→the reactor of the balance section as shownin FIG. 3B.

When the second semiconductor switch 24 of the balance section iscontrolled being turned on and off, voltage of the first condenser 14 israised to an arbitrary value.

In step S4, the control circuit 33 a judges whether or not voltage ofthe first condenser 14 and voltage of the second condenser 14 areequilibrated to each other, the program returns to step S3, and thesemiconductor swicth 24 of the balance section is controlled beingturned on and off as shown in FIGS. 3A and 3B, so that the firstcondenser 14 is electrically charged by the second condenser 15.

In step S5, the control circuit 33 a judges whether or not voltage ofthe first condenser 14 and voltage of the second condenser 15 are raisedto be not lower than a predetermined value, for example, in the case ofoperation at 100 V, the control circuit 33 a judges whether or notvoltage of the first condenser 14 and voltage of the second condenser 15are raised to be not lower than 141 V, and in the case of operation at120 V, the control circuit 33 a judges whether or not voltage of thefirst condenser 14 and voltage of the second condenser 15 are raised tobe not lower than 180 V. In the case where voltage of the firstcondenser 14 and voltage of the second condenser 15 are lower than thepredetermined value, processing in steps S1 to S4 is executed, so thatthe second condenser 15 and the first condenser 14 are electricallycharged.

In the case where voltage of the first condenser 14 and voltage of thesecond condenser 15 are not lower, than the predetermined value in step5, the control circuit 33 a changes over theAC-electric-power-supply/battery changeover switch 5 to the contact “a”so as to connect with the AC electric power supply, and operation isconducted by the AC electric power supply 1. In this case, the batteryoperation switch 27 is kept open as it is opened at the time of start.

In this connection, the above explanations are made into an example ofthe uniterruptible electric power supply using a half bridge circuit inwhich the connecting point of the semiconductor switches connected inseries composing the inverter section is connected with the common lineby which one end of the AC electric power supply and one end of the ACoutput are connected with each other, and both ends of the semiconductorswitches connected in series composing the inverter section areconnected between the positive electrode side voltage line and thenegative electrode side voltage line. However, of course, the presentinvention can be applied to the case of a full bridge circuit.

Industrial Applicability

As described above, according to the present invention, it is possibleto inhibit an inrush electric current without using the inrush electriccurrent inhibiting resistor 3. Therefore, the present invention can beapplied to an uniterruptible electric power supply of small size.Accordingly, the uniterruptible electric power supply of the presentinvention can be suitably used in an office, the space of which must bereduced small.

1. An uniterruptible electric power supply comprising: a common line forconnecting one end of an AC electric power supply with one end of an ACoutput; a positive electrode side voltage line and a negative electrodeside voltage line which respectively become a positive electrode sideand a negative electrode side of DC formed at both ends of diodesconnected with each other in series, a connecting point of the diodesconnected with each other in series being connected with the other endof the AC electric power supply; a first condenser connected between thecommon line and the voltage line on the positive electrode side; asecond condenser connected between the common line and the voltage lineon the negative electrode side; a battery, the negative electrode sideof which is connected with the common line; a negative electrode sideboosting section semiconductor switch, one end collector side of whichis connected with the positive electrode side of the battery; a negativeelectrode side boosting section reactor connected between the other endemitter side of the negative electrode side boosting sectionsemiconductor switch and the common line; a negative electrode sideboosting section diode, one end on the cathode of which is connectedwith the other end on the emitter side of the negative electrode sideboosting section semiconductor switch, the other end on the anode sideof which is connected with the negative electrode voltage line; a firstsemiconductor switch of a balance section and a second semiconductorswitch of the balance section connected with each other in seriesbetween the positive electrode voltage line and the negative electrodevoltage line; a first diode of the balance section and a second diode ofthe balance section which are respectively connected with the firstsemiconductor switch of the balance section and the second semiconductorswitch of the balance section in reverse parallel with each other; areactor of the balance section connected between a contacting point, atwhich the first semiconductor switch of the balance section and thesecond semiconductor switch of the balance section are contacted witheach other, and the common line; and a control section for turning onand off the negative electrode side boosting section semiconductorswitch and the second semiconductor switch of the balance section,wherein after the second condenser is electrically charged by thebattery when the negative electrode side boosting section semiconductorswitch is turned on and off at the time of start, the secondsemiconductor switch of the balance section is turned on and off so asto electrically charge the first condenser by utilizing voltage of thesecond condenser.
 2. An uniterruptible electric power supply accordingto claim 1, wherein the control section changes over the electric powersupply to the AC electric power supply after voltage of the firstcondenser and voltage of the second condenser are equilibrated to eachother and raised to a predetermined voltage.
 3. A method of starting anuniterruptible electric power supply comprising: a first step in which asecond condenser is electrically charged to a voltage not lower than apredetermined voltage by using a battery at the time of start in which afirst condenser connected between a common line, which connects one endof an AC electric power supply with one end of an AC output, and apositive electrode voltage line is not electrically charged and thesecond condenser connected between the common line and the negativeelectrode voltage line is not electrically charged; a second step inwhich the first condenser is electrically charged by utilizing voltageof the second condenser until voltage of the first condenser and voltageof the second condenser are equilibrated to each other; and a third stepin which processing of the first and second steps is successivelyconducted until voltage of the first condenser and voltage of the secondcondenser are raised to a value not lower than a predetermined value,and electric power input is changed over from the battery to the ACpower supply at the point of time when voltage of the first condenserand voltage of the second condenser are raised to a value not lower thana predetermined value.